Manufacture of benzoselenocyanine dyes



UNITED STATES PATENT OFFICE MANUFACTURE OF BENZOSELENOCYANINE DYES Walter Zeh, Dessau in Anhalt, Germany, assignor to Agfa Ansco Corporation, Binghamton, N. Y., a corporation of New York No Drawing. Application August 25, 1933, Serial No. 686,857. In Germany February 3, 1931 13 Claims.

My present invention relates to cyanine dyes and more particularly to benzoselenocyanines. It is a continuation in part of my co-pending application Ser. No. 590,772, filed February 3, 1932.

One of its objects is to provide a process of preparing selenazolemethinecyanines. Another object is the selenazolemethinecyanines. Further objects will be seen from the detailed specification following hereafter.

I have found that a selenazolemethinecyanine corresponding with the general formula V=H, alkyl, alkoxy, halide, an acylamino group, benzo X=halide, perchlorate, para-toluene sulfonate,

alkylo-sulfate, nitrate,

is suited for sensitizing a silver halide emulsion. The range of sensitivity of an emulsion comprising a short region of individual sensitivity will be increased, or if the region of individual sensitivity will not be increased by addition of the sensitizer its sensitiveness within the region of individual sensitivity may be increased. The

sensitizers are therefore well suited for sensitizing silver-chloride emulsions which may be used in color photography.

In the general formula V may represent any ;,position in the benzene nuclei, however, the 5 and 6 position and the 5' and 6' position are pre--. ferred. V may be an alkyl, such as methyl, ethyl, etc. or an alkoxy group, for instance, a methoxy or an ethoxy group, or halide or benzo.

be alkyl, for example methyl or ethyl. X can be any suitable anion, for instance, a halide, paratoluene sulfonate, alkylosulfate, perchlorate nitrate, or the like.

The dyes may be prepared by boiling a 2-alkyl- ;benzoselenazole preferably Z-methylbenzoselenazole. .or a substituted 2-alkylbenzoselenazole.

with a fatty acid anhydride, adding the nitrite of an aliphatic alcohol and separating the precipitated dye.

1 The dyes are obtainable according to the de- T may.

sired solubility in form of the bromide, iodide, perchlorate etc. and are used in a quantity as usual for the known sensitizing dyes. This quantity amounts to about 15 to 30 milligrams per 1 kg. of emulsion ready for being cast which contains about 9 per cent of gelatin, 4.5 per cent of silver halide, the rest being water. However, I do not wish to limit my invention to the quantities just indicated, the most suitable amount will in each case be found by a few comparative experiments. The dyes may be added to the emulsion in form of solutions. Suitable solvents are the alcohols, for instance, methyl or ethyl alcohol which may be used anhydrous or diluted with water. The dyes are applied to the emulsion during any stage of its production, however, they are preferably added to the finished emulsion before being cast. The dyes may likewise be added by coating the emulsion with them or by bathing the finished photographic material in a bath in which the dye is dissolved. The dyes are suited for sensitizing an emulsion made according to the boiling process as well as for sensitizing an emulsion made according to the ammonia process.

The following examples serve to illustrate my invention.

Example 1.For producing the dye bis-[3- ethyl-benzselenazole- (2) l -methinecyanine-iodide corresponding to the formula Se Se- 1 ethyl-5-ethoxy-benzselenazole- (2) methinecyanine-iodide corresponding with the formula 7 1 Se Se 6, H E5020 6 002 6 Czh I 7 115 to a boiling solution of 4 grams of 2-methyl-5- ethoxy-benzselenazole-ethyl-iodide in 30 cc. of acetic anhydride there are added ;1.5 'cc.of ethyl nitrite. While vehemently frothingthe dye separates from the solution in form of yellow flakes.

The dye is obtainable in form of yellow felted" HiC-OC The alcoholic solution of the dye shows an abneedles by recrystallization;iromaalcoholg sorption maximum at a wave .,length of about 440m! Example 3.-The dye bis-[3-ethyl-5'-chloro,- benzselenazole-(2) l-methinecyanine-iodide corresponding with the formulaic 1:

a CzHs' I is precipitated fromtheboiling solution of 4 grams of 2-methyl=5-chloro-benzselenazole-ethyl-iodide in"30cc. of acetic anhydride by addition of 2 cc. of amyl nitrite in form of greenish yellow flakes.

, Recrystallization of the dye from alcohol yields fine needles. 7

The'alcoholic solutionofthe dye shows an absorption maximum at-awave length of about Example 4.=-'-'The 'dyebis- [3-ethyl-6- methoxy benizselenazole- ('2) l-methinecyanine-iodide' corresponding with'the formula separates from a boiling solution, of 4 grams of Zemethyl-G .-methoxy benzselenocyanine iodide and 30 ccfof acetic anliy'olride by addition of 2 cc. oLamylnitrite inform of yellow flakes.

The.alc.ohblic solution; of the pure dye shows an absorption maximum at a wave length of about 435%. Example 5.- For producing the dye bis-[3- methyl-{naphtho lfl' :4.5-selenazo1}- (2) l-methinecyanine-bromide corresponding with the formula l CH

.3- grams: of 2=methyl-a-naphthol-selenaaoleethyl-bromide are heatecliwith'lflecc. of acetic anhydride until boiling. l.- The .dye: separates: ion addition o.1.cc. .of amylmitrite-frfonxthe brown.-

ish yellow colored liquid in form of small crystal..- =-druses. The filteredi product is washed with acemay beobtain ed by heating 3 grams of 2-methyltone and ether and recrystallized from methanol.

The alcoholic solution of the dye shows an absorption maximum at a wave length of about 455mb.

The bases serving as a starting material for 5 the production of the dyes are obtainable according to methods known from the preparation of the unsubstituted benzselenazoles.

Example 6.-The dye bis-[3-methyl-6-acetylamino benzselenazole-(Z) l-methinecyanineio- 10 dide corresponding with the formula V H 7 Se e-- 6 N 15 1 H 5 2 (1) 5 CO.CH|

6-acetylamino-benzoselenazole methiodide in 10 v cc. of acetic anhydride. to boiling and adding 1 cc.

of amylnitrite;

The mixture froths and assumes a brownish: yellow color; the dye separates after cooling.

The alcoholic solution of the dye has an absorption maximum at a Wave length of about 440ml Example 7.The dye bis-[3-methyl-6-propio nylamino benzselenazole (2) methinecyanine iodide-corresponding with the formula may be obtainedby heating 2 grams of 2-methyl- 6-propionylaminobenzoselenazole. methiodide in 10 ccnof acetic. anhydride to boiling and adding 1"cc'. ofethylnitrit. The mixture froths' and assumes a brownish yellow color; the dyesepa- 45" rates after cooling. 7

The al'c'oholicsolution of the dye has an absorption maximum at a wave length of about Example: 8.The dye bis- [3-methyl-5-acety1- 50 amino-benzselenazole- (2)1-methinecyanineiodide corresponding with the formula "ii Jone oooH.. v

limited to. theaforegoing examples nor to the specific details given thereinJ Numerous other. ems-'1 bodiments are -possible'mndvIicontemplate as in-. cluded within my invention all such=,modifica-v tions and equivalents::asifalLwithinv thescope of V stands for a radical selected from the group consisting of H, alkyl, alkoxy, halogen, and alka- 20 cylamino,

X stands for an anion capable of precipitating the dye.

3. A symmetrically substituted compound cor- 25 responding with the formula Se Se it H 1 and having in its alcoholic solution an absorption maximum at a wave length of about 440/141 '7. Bis -[3 ethyl 6 methoxy benzselenazole- (2)l-methinecyanine iodide corresponding with the formula moo Se s OCH: 1 H I 2 2 5 and having in its alcoholic solution an absorption maximum at a wave length of about 435 8. Bis- [3-methy1-{ naphto-1.2' :4.5-selenazole (2) l-methinecyanine bromide corresponding with 1 the formula and having in its alcoholic solution an absorption maximum at a wave length of about 455 9. The process of producing a bis-[3-alkylbenzselenazole- (2) l-methinecyanine salt which comprises boiling the mixture of a quaternary ammonium salt of a 2-methylbenzselenazole with a fatty acid anhydride, adding an alkyl nitrite and separating the formed dye.

10. The process of producing a bis-[3-alkyl-- benzselenazole-(2) l-methinecyanine salt which comprises boiling the mixture of a quaternary ammonium salt of a 2-methylbenzselenazole with acetic anhydride, adding amyl nitrite and separating the formed dye.

11. The process of producing bis-[3-ethyl-5- ethoxy-benzselenazole- (2) l-methinecyanine iodide which comprises boiling a mixture of 2- methyl-5-ethoxy-benzselenazole ethiodide and acetic anhydride, adding amylnitrite, and separating the formed dye.

12. The process of producing bis-[3-ethyl-6- methoxy-benzselenazole- (2) l-methinecyanine iodide which comprises boiling a mixture of 2- methyl-S-methoxy-benzselenazole ethiodide and acetic anhydride, adding amylnitrite, and separating the formed dye.

13. The process of producing bis-[3-methyl- {naphto 1' .2 4.5 selenazole} (2) l methinecyanine bromide which comprises boiling a mixture of 2-methy1- [naphto-1.2' 24.5-selenazolel ethyl bromide and acetic anhydride, adding amylnitrite, and separating the formed dye.

WALTER ZEH. 

